1. Field of the Invention
The present invention relates to a door opening/closing device installed in a door of a building to be opened/closed about a hinge fixed at one side of the door. More particularly, in the door which is manually opened but closed by an automatic returning device, the door opening/closing device regulates the door to be opened in a joggling manner but slowly closed as rotating speed of the door gradually decreases, thereby solving problems occurring at the time of closing the door. The door is securely fixed in a closed position thereby preventing a gap which occurs between the door and a door frame as the door plays due to external force such as wind. Further, the door is securely fixed even if it is completely open.
2. Description of the Related Art
A revolving door known in the related art has a structure that the door is opened/closed in one direction while rotating about a hinge attached to one side of the door. An automatic structure of an opened door has adopted a door check fastened to both of the upper end of the door and a door frame or a coil spring connected to a hinge axis. Also, a device using a pneumatic or air cylinder has been known for the above structure. However, a conventional door opening/closing device using the foregoing structure has the following problems. In the door check which is externally mounted to the door for automatically closing the door, the door check is externally exposed and has a poor aesthetic appearance. Further, frequent failures and noises take place to the door check since a connecting rod is distanced away from the cylinder thereby suffering excessive force. In the structure that the pneumatic or air cylinder is mounted into a housing in which the door hinge is embedded, a high mounting cost is consumed while a piston of the cylinder is easily abraded preventing smooth operation. In the structure employing the coil spring, heavy noises and high failure rate take place as drawbacks.
In particular, the automatic door returning device has the following drawbacks. Although rotating speed of the door can be manually adjusted when the door is opened, rotating speed is uniform unless the door is held because the device does not have a controlling device. Therefore, frequently, the rotating door causes injuries, or a person may be caught between the door and the door frame accordingly having a damage.
A fixing system for holding the door in a position that the door is completed opened or closed does not provide intensity adjustment for fixing the door so that a door reciprocates several times about the center of the door frame before being closed instead of directly stopping at the center due to resilience of rotation of the door. This repeatedly produces gaps and the door stops only after resilience is exhausted. Further, when external force such as wind is applied, the door is slightly opened producing a gap as a drawback.
Further, also in the opened position of the door, the door is not securely fixed so that the door is readily opened under the slightest amount of force applied to the door.
Accordingly the present invention has been devised to solve the foregoing problems of the door opening/closing device of the related art.
According to the invention, when a door is opened, the door starts opening in a heavy and slow manner but is opened at a high speed due gradually increasing rotation speed. On the contrary, when the door is closed, the door stars closing in a light and fast manner but is closed in a slow and heavy manner at a final stage of closing. A returning device which operates when the door is opened/closed is so structured that only one side thereof operates according to opening/closing direction of the door, thereby enabling smooth operation or the device and without a failure. Further, the door can be securely fixed at both of closed and opened positions.